Apparatus for drilling boreholes with explosive charges



Feb. 27, 1962 L. H. ROBINSON, JR 3,022,729

APPARATUS FOR DRILLING BOREHOLES WITH EXPLOSIVE CHARGES Filed Nov. 27,1959 2 Sheets$heet 1 .Z JJMLM ATTORNEY.

Feb. 27, 1962 L. H. ROBINSON, JR

APPARATUS FOR DRILLING BOREHOLES WITH EXPLOSIVE CHARGES 2 Sheets-Sheet 2FIG.?

Filed Nov. 27, 1959,

FIG.3.

FIG.4.

ATTORNEY- INVENTOR. L EON H. ROBINSON JR t I I I I I I I I I i I staticpressure of at least 1000 p.s.i.

United States Patent 3,022,729 APPARATUS FOR DRILLING BOREHOLES WITHEXPLOSIVE CHARGES Leon Haynsworth Robinson, In, Houston, Tex., assignor,by mesne assignments, to Jersey Production Research Company, Tulsa,01th., a corporation of Delaware Filed Nov. 27, 1959, Ser. No. 855,616 4Claims. (Cl. 102-20) This invention relates to the drilling ofboreholes, and more particularly to drilling boreholes utilizing asuccession of explosive charges including shaped jet charges.

In connection with drilling boreholes for the purpose of exploitingpossible hydrocarbon deposits in the earth, it has been known to utilizeexplosive charges for the purpose of expediting drilling operations. Ithas also been known to use shaped jet charges in combination withnondirectional'blasting charges. Examples of the prior art use ofexplosive charges for drilling operations may be found in US. Patent No.2,897,756 to L. Borins et al. and U.S. Patent No. 2,587,243 to W.Sweetman.

Previous attempts to use explosive charges for earth drilling have beencharacterized by very slow penetration rates, great expense, and thenecessity for using more or less cumbersome equipment. While thedevelopment of shaped jet charges has made the use of explosives fordrilling more attractive because of the directional characteristics ofthe shaped charge, it has not proved to be a cure-all for thedeficiencies of explosive drilling. A prime reason is that, while theshaped charge is capaable of penetrating further into the earth than cana nondirectional explosive charge, it blasts a hole that is quite wideat its mouth but which narrows rapidly and terminates in an elongatedcavity that is far too narrow to accommodate a well or drill pipe. Theuse of blasting charges in the manner taught by the aforecited Borins etal. patent has not particularly helped the situation because theblasting charges do not deepen orwiden the hole drilled by the shapedcharge to any great extent.

The present invention makes use of a well pipe having a landing seat ornipple at or near its lower end. The well pipe is connected toconventional mud circulating equipment at the surface so that drillingfluid is pumped down the well pipe and up the annulus around the wellpipe. Use is made of elongated shaped jet charges and elongatednon-directional gauging charges adapted to be pumped down the well pipe,and further adapted to seat on the landing nipple or seat so that adifferential pressure is built up thereacross.

The jet charges and gauging charges are injected into the stream ofdrilling fluid going down the well pipe, according to a predeterminedsequence. First, a shaped charge is pumped down the well pipe. After itseats on the landing seat, the explosive portion of the jet charge isspaced from the bottom of the borehole a predetermined distance, and apressure of predetermined magnitude is built up across the shapedcharge. Responsive to differential pressure, the charge is detonated soas to blast a hole in the earth at the bottom of the well bore. Agauging charge is then landed on the seat so as to extend into the holeproduced by the preceding shaped jet charge. Preferably, the gaugingcharge is long enough to penetrate substantially the entire length ofthe hole blasted by the shaped charge. The gauging charge, which may beof a brisant or unbrisant explosive material or a combination thereof,is detonated while tamped with drilling fluid and preferably while undera hydro- Drilling fluid is circulated after each detonation of a shapedcharge and a gauging charge so as to remove earth fragments andfragments of the explosive charge housing. Preferably,

3,022,729 Patented Feb. 27, 1962 "ice '2 so as to be spaced apartsubstantially 100 to 4000 feet, and the drilling fluid is circulated sothat particles therein are traveling at the rate of between 100 and 400feet per minute so that the successive explosive charges are detonatedbetween 1 and 10 minutes apart.

The invention will be more completely understood, and the variousobjects and features of the invention will become apparent uponconsideration of the following description thereof when taken inconnection with the accompanying drawings, wherein:

FIG. 1 is a perspective diagram of a portion of equipment that may beused at the earths surface in connection with the practice of theinvention;

FIG. 2 is a view of a shaped jet charge being pumped I down a well pipe,showing a preferred construction of the lower end of the well pipe;

FIG. 3 is a side view, partially in cross-section, of a preferred jetcharge capsule to be used in connection with the invention;

FIG. 4 shows certain details of the firing collar shown in FIG. 3;

FIG. 5 is a side view of a portion of the firing collar of FIG. 3;

FIG. 6 is a cross-sectional view showing the differential pressureresponsive firing mechanism shown in FIG. 3;

FIG. 7 is a side view, partially in crossectic; of a gauging charge tobe used in connection with the present invention.

In FIG. 1 there is shown surface equipment for use in connection withthe present invention. The usual drilling rig 1 is provided with anexplosive charge loader's platform 3 at a distance above the drillingfloor 20 determined by the length of well or drill pipe to be run intothe hole to be drilled with the apparatus. An explosive charge housing 5for storing explosive charges is located on the loaders platform 3.

The usual traveling block 9 is suspended from a crown block (not shown)by cables in the usual manner. Lo-

- cated between the swivel 19 and book 10 is an explosive the explosivecharges are injected into the drilling stream charge magazine housing17. Connected to swivel 19 is a Kelly joint 18 which extends through therotary table 21 into the surface casing 25. The function of the magazinehousing is to provide remotely controlled apparatus for injecting aplurality of explosive charges into the well according to apredetermined sequence. Drilling fluid is circulated through themagazine housing 17 into the swivel l9 and Kelly joint 18 from the usualstandpipe 15 and hose connection 13. A mud pump (not shown) suppliespressurized drilling fluid to the standpipe. Below the drilling floor 20is located the usual mud return line 27 which may be controlled by avalve 29. The mud control line is hydraulically coupled to the annularspace around the drill pipe in the usual manner.

As shown most perspicuously in FIG. 2, the drill or well pipe 28 isprovided with a landing seat 31 at or near its lower end. The purpose ofthis landing seat is to receive a collar 45 fitted around an explosivecharge 33 which is pumped down the well. When the collar 45 lands on theseat 31, flow of drilling fluid down through and out the lower end ofthe well pipe will be either stopped or substantially reduced so that adiflerential pressure will be built up across the explosive charge. Aswill be described in detail below, difierential pressure is used for thepurpose of firing the explosive charge.

The details of the explosive charge magazine housing 17 are described incopending application Serial No. 855,681 of L. H. Robinson and R. H.Friedman, filed concurrently herewith.

FIGS. 3, 4, 5, and 6 illustrate a preferred embodiment for the shapedjet charge, its container, and the firing collar illustrated'in FIG. 2.As shown in FIG. 3, the brisant explosive charge material 43 isencapsulated in a housing or container 33 along with the usual boostercharge 41 and detonator 39. In addition, there is provided a firingmechanism 37 for the purpose of firing the detonator 39 responsive to apredetermined differential pressure across the opposed ends of theexplosive charge container. The details of the firing mechanism will bedescribed below with reference to FIG. 6. Inasmuch as the use of ashaped jet charge is contemplated, the usual conical liner 47 isprovided. At the upper and lower ends of the container 33 there areprovided stop members 35 and 49. The purpose of the stop members is tohold a seating ring or firing collar 45 on the charge container. Thefiring collar is longitudinally slidable along housing 33 and has atapered lower surface for the purpose of seating on the seat 31 at thebottom of the drill pipe so that a differential pressure can be producedacross the charge. A frangible sleeve 46 is attached to the upper end ofcollar 45 by a suitable adhesive, the sleeve 46 serving to keep thecollar 45 properly aligned on the housing 33. The details of the firingcollar are best illustrated in FIGS. 4 and 5. The firing collar isformed of members 53 and 55 and locking members 57 and 59. The purposeof the locking members is to prevent the firing collar from coming apartbefore the charge is fired and to permit the firing collar to collapseinwardly when the container is destroyed by firing the charge. As shownin FIG. 5, the outer edges of the locking members have a V shape so thatthey will not drop away from the members 53 and 55 when in lockingengagement therewith.

The details of the firing mechanism are shown in FIG. 6. The firingmechanism includes a housing 63 having an inlet tube 64 open to boreholepressure, and an outlet tube 73 opening into a low pressure tube 77. Thelow pressure tube 77 extends the length of the shaped charge containerto the bottom of the container so that it is exposed to the pressureoutside of the drill pipe when the firing collar 45 is seated on seat31. The outlet tube 73 extends into the interior of the housing 63. Aflexible, resilient diaphragm 61 of rubber-like material such asneoprene seals the inlet tube 64. A similar diaphragm 75 seals theoutlet tube 73. The interior of the housing 63 thus is fluid-tight andis filled with water, glycerin, or other suitable, substantiallyincompressible liquid. A release collar 65 is in sliding fit over thetube 73. A spring 71 normally biases the release collar 65 away from thetube 73 so that it engages the tube 64 of the inlet port. A firing pin67 is pivoted about a pivot member 69 and is springbiased by means ofspring 68 to rotate counterclockwise as shown in FIG. 6. The firing pinwill be released when release collar 71 is moved to the right so as tostrike detonator 39 at one end of its are of movement. The releasecollar is moved to the right when a sufficiently large differentialpressure exists between the inlet tube 64 and the low pressure tube 77.The differential pressure will cause diaphragm 61 to bulge downwardlyinto the housing 63 so as to force the release collar to the right andrelease the firing pin 67 so that it will strike the detonator 39.

The diaphragms 61 and 75 are not absolutely necessary, but serve to keepclean fluid around the working parts of the firing mechanism. This isdesirable to insure that the firing mechanism will function properly.

FIG. 7 illustrates a gauging charge particularly adapted for use withthe present invention. The gauging charge comprises a housing 78 similarto the housing used with the shaped charge. A firing collar 45a isprovided that is similar to firing collar 45. A frangible sleeve 46a isalso attached to the collar 45a. The firing mechanism 37a may besubstantially the same as firing mechanism 37. A low pressure tube 77aextends from the firing mechanism 37a to the lower end of the chargecontainer in the same manner as described above with respect to lowpressure tube 77. A substantial section of the lower portion of thecontainer is filled with a brisant or unbrisant explosive material or amixture of brisant and unbrisant explosives. There is no conical linerprovided with the device so that the explosive effects of the gaugingcharge are substantially nondirectional. A stop is provided above thetopmost level of the explosive so that firing collar 45a will land onseat 31 in such a manner that the topmost level of the explosive chargewill be spaced from the bottom of the well pipe. The housing 78 is alsoprovided with an upper stop 84. This construction is for the purpose ofpreventing damage to the well pipe when the explosive charge isdetonated. The container may be formed of a frangible material so as tobe destroyed easily. The blasting cap 79, when struck by firing pin 67,will be detonated and will ignite a length of primacord 81. Tofacilitate destruction of the container, the primacord may be wound in aspiral around the inner surface of the container. Also, an auxiliarydisintegrating charge 83a of tetryl or like material may be used tocomplete the destruction of the container. The container may be formedof a plastic material. A particularly suitable explosive for use inconnection with the gauging charge is PETN or composition B (RDX andTNT). Other suitable explosives may be found on page 4 of the text TheScience of High Explosives by M. A. Cook (Reinhold Publishing Company,1958). The length of the lower end of the container 78 containing theexplosive preferably is long enough to extend substantially the lengthof the hole blasted by the shaped charge.

The operation of the apparatus described in FIGS. 1 through 7 is asfollows. Before the apparatus described above is used, a borehole may bedrilled in the earth through the relatively soft earth formations nearthe earths surfaces by means of conventional rotary drilling equipment.Alternatively, the apparatus described above may be utilized from thetime that the well is spudded. However, it usually will be found to bemore economical to use a rotary drilling procedure for the initialstages of drilling the borehole until relatively hard earth formationsare encountered.

When a hole has been drilled to a desired depth in the conventionalmanner, the rotary drill pipe may be pulled out of the hole and athinner walled pipe 28 such as shown in FIG. 2 may be substitutedtherefor. An advantage associated with utilizing thinner walled pipe isthat larger explosive charges can be run down the pipe. The lower standof the pipe may be provided with reamer blades 28a for the purpose ofreaming the hole should such become necessary. Likewise, the lowermostedge of the pipe may be studded with diamonds to rotary-drill for shorttime intervals should relatively soft earth formations be encountered.

Initially, a shaped charge 33 from magazine housing 17 is injected intothe drilling fluid stream. At intervals of approximately 1 to 10minutes, the driller may inject the other charges from the magazinehousing 17 into the fluid stream. When a shaped charge is seated at thebottom of the well pipe, manifestly the differential pressure across theshaped charge will detonate the charge as described above. An elongatedtapered hole will be produced. Drilling fluid circulation will continueso that detritus including earth fragments, fragments of the shapedcharge container, and fragments of the firing collar 45 will becirculated up the annulus around the well pipe.

One or more gauging charges are landed in succession at the bottom ofthe pipe after each shaped charge. It will be found that one gaugingcharge is sufficient to enlarge the entire hole to a desired diameter.As mentioned above, the gauging charges should extend substantially tothe bottom of the hole formed by the jet charge. Collar 45a, inasmuch asit is slidable along at least a portion of the gauging charge container,will readily seat on the seat 31 so that a differential pressure willbuild up to detonate the gauging charge. Manifestly, the gauging chargewill be tamped; a hydrostatic pressure of at least 1000 psi. will beexerted thereon. When a gauging charge is detonated, it will be foundthat an almost perfect cylindrical hole will be blasted into the earthformations by the gauging charge. The hole will be amazingly uniform indiameter and will be of a sulficiently large diameter so that the wellpipe 28 may be lowered to the depth of the hole blasted by the shapedcharge 33. It will be found that. by virtue of the fact that the gaugingcharge is tamped and under hydrostatic pressure, the volume of earththat is spalled by the gauging charge will be between 50 and 100 percentgreater than when the explosive charge is not tamped and is not underhydrostatic pressure. A hydrostatic pressure of at least 1000 pounds hasbeen found to be satisfactory. Much higher hydrostatic pressures may beutilized with the effectiveness of the gauging charge increasing as thehydrostatic pressure is increased. Detritus produced by the gaugingcharge may be circulated out of the hole formed as described above, asthe well pipe is lowered.

The invention is not to be restricted to the specific structuraldetails, arrangement of parts, or circuit connections herein set forth,as various modifications thereof may be efl'ected without departing fromthe spirit and scope of this invention.

What is claimed is:

1. An explosive charge capsule for injection into a well pipe having aseating surface at the lower end thereof, comprising: an elongatedhousing having a compartment for an explosive charge material; anannular seating ring slidably afiixed to the elongated housing andlongitudinally slidable along the housing, adapted to seat on theseating surface of the well pipe to substantially seal the well pipeagainst fluid flow downwardly therethrough; a firing apparatus enclosurein said capsule; an inlet line hydraulically coupling the exterior ofthe upper portion of the capsule to the interior of the enclosure; anoutlet line extending into said enclosure hydraulically coupling theinterior of said enclosure to the exterior of the lower portion of saidcapsule; a sleeve in said enclosure slidably fitting over the end ofsaid outlet line, and having a closed end; a coil spring within saidsleeve biasing the closed end of said sleeve away from the end of saidoutlet line within said enclosure, yieldable under differential pressurebetween said outlet line and said inlet line so that the closed end ofsaid sleeve slides toward said end of said outlet line; first and secondresilient diaphragms respectively sealing the interior of said inletline and the interior of said outlet line so that said enclosure isfluidtight; a substantially incompressible fluid within said enclosure;a detonating charge extending into said enclosure and into saidcompartment for detonating explosive material within said compartment; afiring pin pivotally supported within said enclosure positioned tostrike said detonating charge at one end of its arc of movement, saidfiring pin being positioned relative to said sleeve so that said sleeveprevents rotationof said firing pin toward said one end of its are ofmovement from the other end of its arc of movement until a predetermineddifierential pressure between said inlet line and said outlet line movessaid sleeve a predetermined distance toward said end of said outletline; and spring means biasing said firing pin for pivotal movement toengage said sleeve and strike said firing pin.

2. An explosive charge capsule for injection into a well pipe having aseating surface at the lower end thereof, comprising: an elongatedhousing having a compartment for an explosive charge material; anannular seating ring slidably afiixed to the elongated housing andlongitudinally slidable along the housing, adapted to seat on theseating surface of the well pipe to substantially seal the well pipeagainst fluid flow downwardly therethrough; a firing apparatus enclosurein said capsule; an inlet line hydraulically coupling the exterior ofthe upper portion of the capsule to the interior of the enclosure; anoutlet line extending into said enclosure hydraulically coupling theinterior of said enclosure to the exterior of the lower portron of saidcapsule; a sleeve in said enclosure slidably fitting over the end ofsaid outlet line, and having a closed end; a coil spring within saidsleeve biasing the closed end of said sleeve away from the end of saidoutlet line within said enclosure, yieldable under difierential pressurebetween said outlet line and said inlet line so that the closed end ofsaid sleeve slides toward said end of said outlet line; a detonatingcharge extending into said enclosure and into said compartment fordetonating explosive material within said compartment; a firing pinpivotally supported within said enclosure positioned to strike saiddetonating charge at one end of its are of movement, said firing pinbeing positioned relative to said sleeve so that said sleeve preventsrotation of said firing pin toward said one end of its arc of movementfrom the other end of its are of movement until a predetermineddifferential pressure between said inlet line and said outlet line movessaid sleeve a predetermined distance toward said end of said outletline; and spring means biasing said firing pin for pivotal movement toengage said sleeve and strike said firing pin.

3. An explosive charge capsule for injection into a well pipe having aseating surface at the lower end thereof, comprising: an elongatedhousing having a compartment for an explosive charge material; anannular seating ring slidably afiixed to the elongated housing andlongitudinally slidable along the housing, adapted to seat on theseating surface of the well pipe to substantially seal the well pipeagainst fluid flow downwardly therethrough; a firing apparatus enclosurein said capsule; an inlet line hydraulically coupling the exterior ofthe upper portion of the capsule to the interior of the enclosure; anoutlet line extending into said enclosure hydraulically coupling theinterior of said enclosure to the exterior of the lower portion of saidcapsule; a sleeve in said enclosure slidably fitting over the end ofsaid outlet line, and having a closed end; a coil spring within saidsleeve biasing the closed end of said sleeve away from the end of saidoutlet line within said enclosure, yieldable under differential pressurebetween said outlet line and said inlet line so that the closed end ofsaid sleeve slides toward said end of said outlet line; a detonatingcharge extending into said enclosure and into said compartment for detonating explosive material within said compartment; and a spring-biasedfiring pin biased so as to strike said explosive charge at one extremityof its path of movement, and positioned relative to said sleeve so thatsaid sleeve holds said firing pin away from said detonating charge untila predetermined differential pressure exists between said inlet line andsaid outlet line whereby said firing pin will be released to strike saiddetonating charge.

4. An explosive charge capsule for injection into a well pipe having aseating surface at the lower end thereof, comprising: an elongatedhousing having a compartment for an explosive charge material; anannular seating ring operatively associated with said elongated housingadapted to seat on the seating surface of the well pipe to substantiallyseal the well pipe against fluid flow downwardly therethrough; a firingapparatus enclosure in said capsule; an inlet port hydraulicallycoupling the exterior of the upper portion of the capsule to theinterior of the enclosure; an outlet port extending into said enclosurehydraulically coupling the interior of said enclosure to the exterior ofthe lower portion of said capsule; a sleeve in said enclosure slidablyfitting over the end of said outlet port, and having a closed end; acoil spring within said sleeve biasing the closed end of said sleeveaway from the end of said outlet port within said enclosure, yieldableunder difierential pressure between said outlet port and said inlet portso that the closed end of said sleeve slides toward said end of saidoutlet port; a detonating charge extending into said enclosure and intosaid compartment for detonating explosive material within saidcompartment; and a spring-biased firing pin biased so as to ReferencesCited in the file of this patent strike said explosive charge at oneextremity of its path UNITED STATES PATENTS of movement, and positionedrelative to said sleeve so that said sleeve holds said firing pin awayfrom said detonating 448902 Yorke 1891 charge until a predetermineddifferential pressure exists 5 2555993 Spencer 1953 between said inletport and said outlet port whereby said 2'749'840 Babcock June 121 1956firing pin will be released to strike said detonating charge. 2'911'909Fuchs 1959

